STORMWATER QUALITY CONTROL PLAN (SWQCP)

Transcription

1 STORMWATER QUALITY CONTROL PLAN (SWQCP) SPERRY ROAD EXTENSION FRENCH CAMP RD. TO PERFORMANCE DR. CITY OF STOCKTON COUNTY OF SAN JOAQUIN Prepared at the Request of: CITY OF STOCKTON PUBLIC WORKS DEPARTMENT 22 East Weber Street Stockton, Ca Prepared by: 711 N. Pershing Avenue Stockton, CA (209) Date Revised: October 14, 2010

2 Table of Contents BACKGROUND... 1 OWNER S CERTIFICATION STATEMENT... 2 PROJECT DESCRIPTION... 3 PROJECT CATEGORY... 3 PROJECT NARRATIVE... 4 STORMWATER POLLUTION CONTROL MEASURES... 5 GENERAL SITE DESIGN CONTROL MEASURES SITE-SPECIFIC SOURCE CONTROL MEASURES VOLUME REDUCTION MEASURES LID TREATMENT CONTROL MEASURES CONVENTIONAL TREATMENT CONTROL MEASURES CONCLUSIONS... 7 MAINTENANCE PLAN AND RESPONSIBILITY... 8 APPENDIX...9 ii

3 Background The purpose of this report is to demonstrate statutory compliance with the City of Stockton s & County of San Joaquin s Stormwater Quality Control Criteria Plan (Plan), last revised March This Plan is the City s and County s adopted program pursuant to governmental regulations under the Federal Water Pollution Control Act (also know as the Clean Water Act), amended As part of that Act, qualifying public agencies are required to obtain a Phase 1 municipal National Pollutant Discharge Elimination System (NPDES) permit from the Regional Water Quality Control Board (RWQCB). Under that permit, the local agency are required to develop, administer, implement, and enforce a Planning and Development Program to reduce pollutants in runoff from new development and redevelopment projects to the maximum extent practicable. In December, 2007, the RWQCB issued the third term of the NPDES permit to the City of Stockton and the County of San Joaquin, which requires that new development and significant redevelopment projects integrate low impact design (LID) strategies and to use a combination of stormwater control measures. The intent of the current Plan is to maintain the runoff volume from the proposed project site, as determined for a specified design storm depth, at or below the pre-project runoff volumes. The current Plan identifies how applicable projects can meet regulation Plan criteria through various volume reduction measures in conjunction with LID treatment controls. Effecive January 1, 2010, the current Plan is applicable to the Stockton Urbanized Areas, which encompass the stormwater drainage system operated by the City, urbanized County areas that are enclosed within the City, and urbanized County areas that surround the City. Project applicability is discussed later in this report. 1

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5 Project Description Project Category Applicable projects, or Priority Projects, fall into one or more of the eight categories summarized as follows: 1. Significant redevelopment defined as the new creation or addition of a least 5,000 square feet of imperviousness on an already developed site. 2. Home subdivisions of 10 housing units or more including residential, commercial and apartment type development. 3. Commercial Building new construction of non heavy industrial nor residential commercial buildings having footprints over 5,000 square feet. 4. Automotive repair shops constructing over 5,000 square feet of imperviousness. 5. Restaurants - constructing over 5,000 square feet of imperviousness. 6. Parking lots - constructing over 5,000 square feet of imperviousness or as having 25 or more spaces potentially exposed to urban runoff. 7. Street and roads defined as any new paved surface used for transportation equal to or greater than 1 acre. 8. Retail Gasoline Outlets - constructing over 5,000 square feet of imperviousness. This project is a Priority Project and it categorically qualifies as both a Significant Redevelopment project and a Street and Roads development. 3

6 Project Narrative This project proposes the new construction of a four-lane public road of approximately 5,400 lineal feet. The intent is to make a transitional connection for Sperry Road between French Camp Road and Performance Drive. The lands affected by this project are primarily flat in topography, and are comprised of business yards, railroads, streets, drainage canals and open spaces. Depending on location, existing drainage occurs through natural and man-made drainage courses, percolation, evaporation and/or public drainage systems draining to a local detention basin. The westerly 4,000 lineal feet of new paving effectively incorporates volume reducing and LID control measures as discussed in this report. Due to environmental reasons, an easterly portion of the project which constructs the Old Sperry Road reconnection, is not allowed to disturb the existing soil and Plan features were not applicable along that portion. Additionally, the easterly 1,400 lineal feet of new paving, which ends at Performance Drive, does not directly incorporate volume reduction and LID control measures, but it should be noted this 1,400-foot portion is a partial reconstruction of an existing road, which already drains to an existing drainage system in the Airport Gateway area and outfalls into a detention basin which ultimately conveys to LittleJohn s Creek. Although not specifically designed for, the detention basin can be considered an indirect treatment control. This report does not include evaluations on the existing detention basin. This report and the attached calculations directly evaluate this project as a whole and independent development, and only relates to the design and features constructed by the project. See the attached site map for additional reference. Specific project information is as follows: Total Project size: Project location: Current Land uses: Pollutants of concern: Existing impervious areas: New impervious areas: 30 acres 5400 S. El Dorado St., Stockton, CA Business yards, railroads, streets, drainage canals and open spaces Likely sediment, metals, trash & debris, with possible oxygen demands 5.4 acres 18.5 acres 4

7 Stormwater Pollution Control Measures This section summarizes the applicability or feasibility of each type of the Best Management Practices (BMPs), volume reduction measures, and/ or treatment control measures considered for the project. This list of measures is taken from Table 2-2 of the current City s Plan. General Site Design Control Measures: G-1 Conserve Natural Areas G-2 Protect Slopes and Channels G-3 Minimize Soil Compaction G-4 Minimize Impervious Areas Site-Specific Source Control Measures: S-1 Storm Drain Message and Signage S-2 Out door Storage Area Design S-3 Trash Storage Area Design S-4 Loading/unloading Dock Area Design S-5 Repair/maintenance Bay Design S-6 Vehicle/Equipment/Accessory Washing Area Design S-7 Fueling Area Design Volume Reduction Measures: V-1 Rain Garden V-2 Rain Barrel/Cistern V-3 Vegetated Roof V-4 Interception Trees V-5 Grassy Channel V-6 Vegetated Buffer Strip LID Treatment Control Measures: L-1 Bioretention Area L-2 Stormwater Planter L-3 Tree-well Filter L-4 Infiltration Basin L-5 Infiltration Trench/Dry Well L-6 Porous Pavement Filter L-7 Vegetated (Dry) Swale L-8 Grassy Swale L-9 Grassy Filter Strip Applied Not Applicable Not Feasible Applied Not Applicable Not Feasible Applied Not Applicable Not Feasible Applied Not Applicable Not Feasible 5

8 Conventional Treatment Control Measures: C-1 Constructed Wetland C-2 Extended Detention Basin C-3 Wet Pond C-4 Proprietary Control Devices Applied Not Applicable Not Feasible G-Series Design Comments: There are no natural areas to conserve. A significant portion of the new road is elevated and the resulting slopes will be protected from erosion pursuant to Caltrans Standard Specifications. There are three sub-drainage areas which outfall to an existing river bank or tributary drainage swale. Each of the three outfall structures incorporates riprap slope protection measures. The project s construction limits were kept to a minimum as the only means of minimizing impervious areas and soil compactions. Because this project is solely for the purposes of a new road, minimizing soil compaction is considered not feasible. Similarly, the paved road width was designed to a regulation minimum and there are no extraneous impervious areas that could be reduced. S-Series Design Comments: As noted on the plans, the storm drain message for all catch basins and drop inlets shall be permanently stamped with the fish logo per the requirements of the City SWQCP, figure 4-1. None of the other source specific design features are included with this project and are therefore not applicable. V-Series Design Comments: Rain barrels, cisterns, vegetated roofs, and interceptor trees were simply not possible with this project. Environmental issues, maintenance responsibilities, economics, and available space, with influence in that respective order, played significant roles in the determination of which volume reduction measures could be incorporated into the design. Vegetated buffer strips were considered but deemed not feasible due to street standards, public safety, and maintenance restrictions. Rain gardens were also considered but deemed not feasible due to space and drainage conveyance limitations as well as irrigation and maintenance restrictions. The project proposes to incorporate approximately 2,700 lineal feet of grassy channels/vegetated (wet) swales. Attached to the end of this report are the volume reduction spreadsheets on the City of Stockton s publicly released VRR calculator. The entire project is broken down into 15 subdrainage areas as shown on the Drainage Exhibit in the Appendix of this report. As explained in the Project Narrative, the easterly portion of the project was not capable of actively incorporate Plan features. The calculation spreadsheet included in this report cover only those first 1 through 10 sub-drainage areas which were able to included Plan features to the maximum extent practical. 6

9 L-Series Design Comments: This project does not directly discharge runoff to a regional treatment facility. The vegetated swales planned with this project shall be installed under the City s SWQCP requirements and maintained under the City s SWQCP guidelines. Each vegetated swale is a minimum 100 foot long trapezoidal channel with a bottom width of 2 feet, side slopes not steeper than 3 on 1, and a longitudinal slope of at least 0.50%. (Note, the attached City spreadsheets do not show enough decimal places to see the design slope value. A custom capacity spreadsheet is also included in the appendix which does show the design slopes.) Pursuant to the City s SWQCP guidelines, the calculated SQDF s have a flow depth ranging from 1 to 5 inches, with and average of around 3.5 inches. Refer to the project specifications for the selected grass species. Each swale was also confirmed as being able to handle the 10-year City of Stockton design storm. Attached to the end of this report are the low impact design (LID) spreadsheets on the City of Stockton s publicly released VRR calculator. Again, the calculation spreadsheet included in this report cover only those first 1 through 10 sub-drainage areas which were able to included Plan features to the maximum extent practical. C-Series Design Comments: The project used no Conventional Treatment Controls. Conclusions Pursuant to the regulations set forth in the current Stormwater Quality Plan, this project incorporates and applies volume reduction and low impact design measures to the maximum extent practical. Subject to reasons explained above, this project was not able to fully meet the project determined volume reduction requirements. Refer to the Volume Reduction Calculator (summary) in the Appendix of this report for details. A Volume Reduction Requirement Waiver Application is requested and is included at the end of this report. 7

10 Maintenance Plan and Responsibility With respect to the development of this project, the immediate property owners and/or persons responsible for the operations and maintenance of this project are as follow: City of Stockton, Public Works Department 22 East Weber Ave., Room 301 Stockton, CA The responsible party(ies) listed above shall adhere to a detailed Maintenance Plan in accordance with Appendix D-2 of the City s SWQCP. 8

11 Appendix Volume Reduction Summary Worksheet 1-page Weighted Runoff Determinations 1-page Volume Reduction Worksheets 10-pages Low Impact Design (LID) Worksheet 10-pages Custom Ditch and Swale Capacity Spreadsheet 2-pages Volume Reduction Requirement Waiver Application 3-pages Colored Site Map 1-sheet Drainage and Swale typical details 2-sheets Drainage Plan Sheets 7-sheets 9

12 City of Stockton/ County of San Joaquin 2009 Stormwater Quality Control Criteria Plan Volume Reduction Calculator (Updated July 16, 2010) Make sure that Macros are enabled while using the Calculator This calculator is solely for the purposes of determining compliance with the Volume Reduction Requirement. This is not a substitute and should not be used to determine compliance with SQDV/SQDF or any other new development/redevelopment requirements. Volume Reduction is only given to Volume Reduction Measures and LID Treatment Controls. Volume Reduction is not given to Conventional Treatment Controls including wet ponds and proprietary controls. The Calculator is intended as a companion to the SWQCCP and not to replace or be independant of it. Therefore all of the details contained within the SWQCCP are not contained within the calculator. Instructions: Fill in the yellow boxes with the requested information. Numbers in the remainder of the boxes will be automatically filled out for you. Each of the following worksheets will assist you in calculating the volume reduction achieved for Volume Reduction Measures and LID Treatment Controls. A worksheet must be filled out for each Volume Reduction Measure and LID Treatment Control (e.g., if there are 3 Rain Gardens proposed on the site, 3 Rain Garden worksheets must be filled out). Once the information is filled out for the proposed Volume Reduction Measures and LID Treatment Controls, click in the red box below. This will run a macro that will sum up the volume reduction achieved by Volume Reduction Measures and LID Treatment Controls. NOTE to Mac Users: The Mac version of Excel may not be capable of running macros so you may have to manually sum up the volume reduction gained from Volume Reduction Measures and LID Treatment Controls. Project: Detail: Design by: Date: Sperry Road Extention Westerly extention of Sperry Road to French Camp Road Kjeldsen Sinnock & Neudeck, Inc. 20-Aug PRE-PROJECT CHARACTERISTICS Total Project Area must be entered first before any other a. Total Project Area, ft 2 (A PRE ) calculations can be made b. Weighted Runoff Coefficient (C rpre ) 0.38 Go to "Cr Calcs" to calculate (orange tab) c. Volume Reduction Requirement storm depth, inches (d) 0.51 Avg. 85th percentile, 24-hour storm depth for Stockton area d. Significant Redevelopment Volume Reduction Credit, inches (Redev credit ) An additive credit of 0.05 inches is available for five types of redevelopment projects: - Siginificant Redevelopment (as defined in Section 2.1 of 2009 SWQCCP) - Brownfield redevelopment - High density (>7 units/acre) - Vertical Density (FAR of 2 or >18 units/acre) - Mixed use and Transit Oriented Development (within 1/2 mile of public transit) e. Revised Volume Reduction Requirement storm depth, inches (d revised ) f. Pre-project Runoff Volume, ft 3 (Vol PRE ) Vol PRE = (d revised /12) x A PRE x C rpre Credits are additive such that a maximum credit of 0.25 inches is possible for a project that meets all five criteria. - New development projects are not eligible for the criteria. 2. POST-PROJECT CHARACTERISTICS a. Total Project Area, ft 2 (A POST ) b. Weighted Runoff Coefficient (C rpost ) Go to "Cr Calcs" to calculate (orange tab) c. Volume Reduction Requirement storm depth, inches (d) 0.51 d. Significant Redevelopment Volume Reduction Credit, inches (Redev credit ) An additive credit of 0.05 inches is available for five types of redevelopment: - Siginificant Redevelopment (as defined in Section 2.1 of 2009 SWQCCP) - Brownfield redevelopment - High density (>7 units/acre) - Vertical Density (FAR of 2 or >18 units/acre) - Mixed use and Transit Oriented Development (within 1/2 mile of public transit) e. Revised Volume Reduction Requirement storm depth, inches (d revised ) f. Post-project Runoff Volume, ft 3 (Vol POST ) Vol POST = (0.51/12) x A POST x C rpost Credits are additive such that a maximum credit of 0.25 inches is possible for a project that meets all five criteria. - New development projects are not eligible for the criteria. VOLUME RUNOFF REDUCTION REQUIREMENT, ft 3 (VRR) VRR = Vol POST Vol PRE VOLUME REDUCTION MEASURES a. Total Volume Reduction from Volume Reduction Measures, ft 3 ( Vol VRM ) b. Remaining Volume Reduction required from LID Treatment Controls, ft 3 (VRR TREAT ) VRR TREAT = VRR Vol VRM Click in red box below to tally the volume reduction achieved by Volume Reduction Measurs and LID Treatment Controls. 4. LID TREATMENT CONTROLS a. Total Volume Reduction from LID Treatment Controls, ft 3 ( Vol TREAT ) b. Total Volume Reduction Provided, ft 3 (VRR PROVIDED ) VRR PROVIDED = Vol VRM + Vol TREAT CLICK IN BOX TO LEFT to tally the volume reduction achived by Volume Reduction Measures and LID Treatment Controls. VOLUME REDUCTION REMAINING, ft 3 (VRR REMAIN ) VRR REMAIN = VRR VRR PROVIDED

13 RUNOFF COEFFICIENT CALCULATIONS Total Site Area must be entered in "Summary Sheet" before you can proceed PRE-PROJECT WEIGHTED RUNOFF COEFFICIENT Site Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Total Area (A element /A PRE ) Weighted Runoff Coefficient (C rpre ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE *Adapted from the Center for Watershed Protection, Ellicott City, MD Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 though 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of the Site (A PRE) POST-PROJECT WEIGHTED RUNOFF COEFFICIENT Site Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Total Area (A element /A PRE ) Weighted Runoff Coefficient (C rpost ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE *Adapted from the Center for Watershed Protection, Ellicott City, MD Select a site element from the drop down list; a corresponding runoff coefficient will appear Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of the Site (A PRE)

14 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D1 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessary to accomodate all the Grassy Channels in the project. To copy this spreadsheet, simply right click on the tab, select "Move or Copy", then Select "Grassy Channel (V-5)", check the "Create a Copy" box, and hit OK. GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.1 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 0.2 iii. Design flow velocity, ft/sec (v GC ) 0.1 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

15 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D2 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.3 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 0.8 iii. Design flow velocity, ft/sec (v GC ) 0.4 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

16 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D3 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) 0.0 Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) c. Design longitudinal slope, ft/ft (s GC ) d. Design length of Grassy Channel, ft (L GC ) 0.0 e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) iii. Design flow velocity, ft/sec (v GC ) V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec 0.0 t ref =7 min g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp 0.0 * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. 0.0 Volume reduction achieved by Grassy Channel

17 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D4 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.3 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 0.9 iii. Design flow velocity, ft/sec (v GC ) 0.4 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

18 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D5 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) 0.0 Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) c. Design longitudinal slope, ft/ft (s GC ) d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) iii. Design flow velocity, ft/sec (v GC ) V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec 0.0 t ref =7 min g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp 0.0 * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. 0.0 Volume reduction achieved by Grassy Channel

19 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D6 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.3 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 1.0 iii. Design flow velocity, ft/sec (v GC ) 0.2 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

20 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D7 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.4 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 1.3 iii. Design flow velocity, ft/sec (v GC ) 0.5 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

21 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D8 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.4 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 1.2 iii. Design flow velocity, ft/sec (v GC ) 0.2 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

22 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D9 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) c. Design longitudinal slope, ft/ft (s GC ) d. Design length of Grassy Channel, ft (L GC ) 0.0 e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) iii. Design flow velocity, ft/sec (v GC ) V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec 0.0 t ref =7 min g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp 0.0 * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. 0.0 Volume reduction achieved by Grassy Channel

23 VOLUME REDUCTION MEASURE: GRASSY CHANNEL (V-5) UNIQUE ID: D10 A separate worksheet must be completed for each Grassy Channel within the proposed development project (e.g., 3 Grassy Channels proposed = 3 separate Grassy Channel worksheets; one for each Grassy Channel). Copy this spreadsheet as many times as necessa GRASSY CHANNEL TRIBUTARY IMPERVIOUS AREA CREDIT* Design Parameter Criteria a. Determine reference SQDF (SQDF ref ) i. Impervious tributary area, ft 2 (A imp ) Amount of impervious cover in tributary area ii. Impervious area runoff coefficient (C imp ) 0.95 Assumes that tributary area is 100% impervious iii. SQDF ref, cfs = 0.2 x A imp x C imp / 43, b. Design bottom width of Grassy Channel, ft (W GC ) 2.0 c. Design longitudinal slope, ft/ft (s GC ) 0.0 d. Design length of Grassy Channel, ft (L GC ) e. Flow SQDF from Manning equation i. Design flow depth, ft (D GC ) 0.3 D ref =0.25 ft ii. Design flow area, ft 2 (A GC ) 0.8 iii. Design flow velocity, ft/sec (v GC ) 0.2 V ref =1 ft/sec f. Contact SQDF, min (t GC ) t GC = L GC / v GC / 60 sec g. Impervious Area credit for Grassy Channel, ft 2 (A credit ) A credit = (D ref /D GC ) 2 x (v ref /v GC ) 2 x (t GC /t ref ) x A imp t ref =7 min * Calculation of the Impervious Area Credit is necessary to determine the volume reduction for Grassy Channels If calculated values of (D ref /D GC ), (v ref /v GC ) or (t GC /t ref ) are > 1.0, the value is set to 1.0 Maximum allowable Area credit = Area imp VOLUME REDUCTION FOR GRASSY CHANNEL Design Parameter Criteria a. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils for C and D soils = 0.25 b. Volume Reduction, ft 3 (Vol reduction ) = (A credit ) x V soils x (0.51/12) 0.25 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability Volume reduction achieved by Grassy Channel

24 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D1 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.23 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils 59.2 Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 13 of 22

25 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.43 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 14 of 22

26 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D3 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.13 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils 75.0 Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 15 of 22

27 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D4 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.42 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 16 of 22

28 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D5 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.13 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils 69.8 Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 17 of 22

29 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D6 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.38 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 18 of 22

30 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D7 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.35 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 19 of 22

31 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D8 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.28 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 20 of 22

32 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D9 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommoda The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.49 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 21 of 22

33 LID TREATMENT CONTROL: GRASSY SWALE (L-8) UNIQUE ID: D10 A separate worksheet must be completed for each grassy swale within the proposed development project (e.g., 3 grassy swales proposed = 3 separate grassy swale worksheets; one for each swale). Copy this spreadsheet as many times as necessary to accommodate all the grassy swales in the project. To copy this spreadsheet, simply right click on the tab, select "Move or Copy", then Select "Grassy Swale (L-8)", check the "Create a Copy" box, and hit OK. The Volume Reduction allowed for Grassy Swales is based on the SQDV. However, please note that the SQDF should be used when sizing Grassy Swales. The following are the steps necessary to calculate the Volume Reduction Requirement for Grassy Swales. 1) GRASSY SWALE DRAINAGE AREA Design Parameter Criteria a. Drainage Area, ft 2 (A drainage ) Drainage area to grassy swale 2) WEIGHTED RUNOFF COEFFICIENT FOR GRASSY SWALE DRAINAGE AREA Identify the area if each element within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Runoff Coefficient* (C r ) Element Area, ft 2 (A element ) Fraction of Drainage Area (A element /A drainage ) Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL SITE Weighted Runoff Coefficient (C ra ) Select a site element from the drop down list; a corresponding runoff coefficient will appear; if you wish to enter your own, please use Other 1 through 3 below Runoff coefficient for permeable pavers will vary. Please consult the manufacturer for appropriate design values. Use Other 1, Other 2, and Other 3 if a particular site element is not included in the drop down list. To do so manually enter the name of the new site element into the row and corresponding runoff coefficient. Make sure the Total for the Element Area column adds up to the Total Area of Drainage Area 3) EFFECTIVE TRIBUTARY AREA Subtract out the Tributary Impervious Area Credits associated with the Volume Reduction Measures located within the Grassy Swale's drainage area. Drainage Area Post-Construction Element Element Area, ft 2 (A element ) Tributary Impervious Area Credit* (A credit ), ft 2 Effective Area (A eff ), ft 2 Asphalt/concrete pavement Managed Turf: Type C/D Soil Permeable Pavement Other1: Other2: Other 3: TOTAL EFFECTIVE AREA (A eff ) *Tributary Impervious Area Credit (A credit ) must be obtained from Volume Reduction Measures (e.g., rain gardens and interception trees) within the tributary area of the grassy swale. A credit was calculated in and can be obtained from the Volume Reduction Measure worksheets. 4) VOLUME REDUCTION FOR GRASSY SWALE Design Parameter Criteria a. Unit Basin Storage Volume (V u ) 0.28 b. Soil Volume Reduction Factor, ft 3 (V soils ) Use one of the following: V soils for A and B soils = 0.50 V soils C and D soils = b. Volume Reduction, ft 3 (Vol reduction ) = (V u x A eff / 12 in/ft) x V soils Obtain unit basin storage volume for 48-hour drawdown using the C ra calculated above and SWQCCP Figure 6-1 V soils is volume reduction factor allowed for infiltration, which varies with soil permeability. - aka SQDV x V soils - Volume reduction achieved by grassy filter strip Page 22 of 22

34 Table V-DITCH CAPACITY CALCULATIONS Side Slope: 2 to 1 n: 0.08 Average Flow Calc Length U/S Invert U/S Top D/S Invert D/S Top Depth Slope X-Area Perimeter Capacity Runoff Sheet Station Side (ft) (ft) (ft) (ft) (ft) (ft) S (ft/ft) A (sf) P (ft) Q (cfs) Qr (cfs) Description 5A-1, (D-1) to LT A2 and A2 side slope LT 5A-1, (D-1) to RT A1 and A2-A3 side slope RT 5A-1, to RT C1-C3 side slope RT (D-1 & 2) 5A-1, (D-2) to RT to LT El Dorado Street Bridge drain D2 5A-2, (D-2) to RT to LT El Dorado Street Bridge drain D3 5A-2, to RT to LT No specified drainage (D-2) 5A-2, (D-2) to RT to LT UPRR Fresno Bridge drain F3 5A-3, to RT G2 side slope RT (D-3 & 4) 5A-3, to RT No specified drainage (D-4) 5A-3, to LT No specified drainage (D-4) 5A-4 & 9, (D-4) to RT to LT L1 and UPRR Oakland Bridge drain H3 & H4 5A-9, (D-4) 5A-9, (D-4) 5A-9, (D-4) 5A-9, (D-4 & 5) 5A-10, (D-5) 5A-10, (D-5) 5A-5, (D-5 & 6) 5A-6, (D-6) to RT to LT L to RT No specified drainage to LT L to LT L to LT to RT P to LT P to LT K side slope LT to LT K side slope LT

35 Table GRASSY SWALE CAPACITY CALCULATIONS Side Slope: 3 to 1 Bottom Width: 2 ft n: 0.08 Average Flow Calc Length U/S Invert U/S Top D/S Invert D/S Top Depth Slope X-Area Perimeter Capacity Runoff Sheet Station Side (ft) (ft) (ft) (ft) (ft) (ft) S (ft/ft) A (sf) P (ft) Q (cfs) Qr (cfs) Description 5A-1, to RT (D-1) A1 and side slope RT 5A-1, (D-1) to LT A2, A3, and side slopes A2 & A3 LT 5A-1, (D-1 & 2) to LT El Dorado St Bridge Drain D1 & D2, & Outlets C2, C3 & C4 5A-2, (D-2) to RT Half of E side slope RT 5A-2, (D-2) 5A-2, (D-2) 5A-2, (D-2) 5A-2,3, (D-2 & 3) 5A-2,3, (7D-2 & 3) 5A-3, (D-3 & 4) 5A-4, (D-4) 5A-4, (D-4 & 5) to LT El Dorado St Bridge Drain D3, Outlet E and half of E side slope LT to RT Half of E side slope RT to LT Half of E side slope LT to RT G1 side slope RT and Outlet G to LT G2 side slope LT and Outlet G2 UPRR Fresno Bridge Drain F1 & F to LT G4 side slope LT to RT I1 side slope RT and Outlet I to RT I2 side slope RT and Outlet I2

36 Appendix C Volume Reduction Requirement Waiver Application A waiver may be granted if the Volume Reduction Requirement cannot be met due to site constraints, such as a high groundwater table. However, even if the project cannot meet the full Volume Reduction Requirement, the project must still reduce volume to the maximum extent practicable. The burden of proof is on the project applicant to show why the full Volume Reduction Requirement cannot be met. Economic hardship is not an acceptable reason for noncompliance. In general, the City and County do not expect to grant waivers for the Volume Reduction Requirement. Meeting the Volume Reduction Requirement is an iterative process. Designers should return to prior steps to explore alternative combinations of Volume Reduction Measures and LID Treatment Controls. Projects that cannot fully meet the Volume Reduction Requirement and are located in a watershed with a 303d listed waterbody, must select Treatment Controls with a medium to high removal efficiency for the pollutant of concern (see Table 6-2). The final determination will be made by City of Stockton Department of Municipal Utilities, Technical Services Division or the San Joaquin County Department of Public Works, Community Infrastructure Division. The City and County have the authority to reject a Volume Reduction Requirement Waiver request if Volume Reduction Measures and/or LID Treatment Controls are considered feasible at the project site. Consideration of a waiver request requires applicants to: Reduce volume to the maximum extent practicable, even if the full Volume Reduction Requirement cannot be met. Consider all of the Volume Reduction Measures and LID Treatment Controls. Applicants must show why certain Volume Reduction Measures and/or LID Treatment Controls are not feasible at the development site. Submit this application with or prior to preliminary site plan submission. Obtain the signature and stamp of the project engineer registered in California. Submit the Volume Reduction Design Summary Worksheet (Appendix B) along with this application. 1. Project Name 2. Project Category (See Section 2 for categories) 3. Property Description (include location, size, land uses, etc.) 4. Owner/Developer s Name Address Phone 5. Plan Preparer s Name Address Phone FINAL Stormwater Quality Control Criteria Plan C-1 March 2009

37 6. Volume Reduction Volume Reduction Requirement (Volume Reduction Summary Worksheet, line 2e) Volume Reduction Provided (Volume Reduction Summary Worksheet, line 4b) Volume Reduction Remaining (Volume Reduction Summary Worksheet, line 4c) Type and Number of Volume Reduction Measures Proposed: Type and Number of LID Treatment Controls Proposed: Rain Garden (V-1) Rain Barrel/Cistern (V-2) Vegetated Roof (V-3) Interception Trees (V-4) Grassy Channel (V-5) Vegetated Buffer Strip (V-6) Bioretention (L-1) Stormwater Planter (L-2) Tree-well Filter (L-3) Infiltration Basin (L-4) Infiltration Trench/Dry Well (L-5) Porous Pavement Filter (L-6) Vegetated (Dry) Swale (L-7) Grassy Swale (L-8) Grassy Filter Strip (L-9) 7. Describe Why a Volume Reduction Requirement Waiver is Needed (please include specifics regarding site constraints e.g., results of any soil testing that may have been done) FINAL Stormwater Quality Control Criteria Plan C-2 March 2009

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